Self-Defense Ammunition: Myths and Magic!

Self-Defense Ammo: What is best?

I have considered this article for a long time. It is one of the most controversial and hotly debated topics in all of firearms lore. There have been numerous studies, much data collection, and millions of words’ worth of acerbic banter tossed back and forth…even BEFORE the internet! On the surface, it seems so easy: Bullets kill bad guys, right? If life was like the old westerns, just shooting the bad guy would make him die, instantly, and with no big mess or hassle. I fondly remember watching Davey Crockett shoot Creek Indians on TV. All he had to do was point, pull the trigger of his perennially loaded musket, and somewhere 200 yards away, a suspiciously pale Native American would clutch his chest and fall dramatically into the river. Imagine my horror, dear reader, when I first purchased a firearm and found out that bullets are not made of magic, and that at the end of the day, all any bullet is, is a hunk of dense metal travelling very fast.

All of the things that the various ammo sizes and types out there can and cannot do are merely a function of two factors: the physics of projectiles, and the biology of the human body. While this concept is simple enough to state, this condition does not simplify anything; rather it complicates things to the point of insanity.

I will try to compile the results of my research here in a concise and explicit manner. I fully understand that the second this article is published, several thousand people will immediately post why I am wrong, and they will each have a study to support their claim. That’s how murky it is out there, folks. I am an engineer by trade, and even I struggle to accept that the reality of self-defense ammunition is this: the entire process of inflicting damage with a firearm has so many holistic factors, that it becomes as much art as science. That being said, your own personal decision can be aided by applying objective science and observation. As with most of the decisions associated with owning a firearm, there will be a trade-off between risk and reward, convenience and confidence, and as always fact and fantasy.

The Physics-

Physics is fun. We damage bad guys by delivering force to their bodies in excess of what the targeted body part can handle. We used to do it with fists, sticks, swords, ad naseaum. No force, no damage. The great oversimplification with respect to force is this: Force will always equal mass times acceleration. You can’t really argue that; beyond the fact that the relationship is rather more complex. For the sake of argument, it is safe to say that force is a function of the product of mass and velocity. I could point out that the velocity is a function of both speed AND direction, but I am trying to keep this simple! The velocity of the mace’s head is multiplied by its mass to create the force. You swing faster, you hit harder. Obviously, most defense ammunition for man-portable weapons system has comparatively small mass as compared to, say, a battle axe or war hammer. It is a good thing then, that force varies with the square of velocity. Basically, increasing the velocity a little bit, increases the force by a lot. At the end of the day, to increase the force our weapon delivers to the target, we must increase either mass or velocity.

Easy, right? Nope. We ain’t done, yet. Force is great. Love force. Good times. Force can certainly break stuff, but if you really want to smash something/one you can deliver the force a couple of different ways. You can increase impulse if you like. Impulse is defined as imparting a change in momentum, or force divided by time. Basically, the same force delivered quickly (over a shorter period of time), will cause greater impulse to the material than one applied gradually. Would you rather be pushed or punched? By delivering force rapidly, we can exceed the breaking strain of materials (human bone and organ tissue for instance) more easily.

When bullets hit humans, all the force is not delivered instantly. If it was, the results would be...well...awesome. All the math dorks out there know that if time interval T approaches 0, than impulse will approach infinity. An infinite impulse would probably rip a hole in spacetime. That is a bad-ass bullet! What we end up with out here in the real world is an inelastic collision. This means one or both of the colliding objects deforms, collapses, breaks and/or fails, consuming some of the energy, and in this scenario, increasing the interval of time the force is in effect. Astute readers have already figured out that the longer the force is applied, the smaller the impulse. It’s exactly what happens when a stuntman jumps off a building onto a big air mattress. Same mass, same velocity as hitting the concrete, but the mattress increases the time interval that the force (of the fall) is applied across his body. This is also part of the reason why despite the fact that you hear that a bullet can strike with “400 foot-pounds” of force, you don’t see stories of 160 pound people getting thrown through the air by bullets. The person deforms, the bullet deforms, and the impulse is reduced greatly, which imparts much less momentum to the target. Furthermore, in any collision the lion's share of energy will go to the object with less mass. Ergo, the bullet goes flying, not you.

You swing a ball at one end, and the force travels instantly all the way through the ball at the other end, the impulse stays high because the time the force is applied remains brief (This is an elastic collision). This is possible because the balls don’t deform, and the energy can travel instantly and effortlessly. If you made one of those balls out of, say foam; it would not transmit the force, rather the force would be dragged out over time whilst deforming the foam ball. All that energy would go into the aforementioned deformation, and never get to the other end. Now imagine the foam ball is your liver. Get the point?

Another way to break something is is pressure, which is force divided by area. Smaller areas, yield greater pressures for the same quantity of force. Pressure can cause failure just like impulse can. This is why pointy things hurt more than blunt things. If I have to explain that to you, then you are not ready for firearms ownership. Pressure is why we make bullets pointy. This way they tear through skin and muscle to penetrate deeply. We would not want to waste all that destructive energy close to the surface, would we?

Why do we care about the physics? Because we can calculate mass, pressure and acceleration for our bullets, and thus have a solid number to start with. Impulse, however, is a factor that will be unique to every single shot. The density of the target, the angle, the distance, as well as many other factors will all factor into the impulse generated by the bullet, and subsequently will affect the nature and overall lethality of the wound. We could also mention that all these forces are acting in three dimensions, but vector calculus is soooooooo tedious, and no one wants me to go into that.

The Biology

Human beings are squishy. This has preserved us more than you realize. By having relatively soft exteriors, we automatically increase the duration of any force applied to us, reducing the impulse and resisting structural failure of our skin, organs, and bones. It’s a good system, one that we as humans, have sought to defeat since the dawn of time. We figured out that pointy things defeat this by taking a small amount of force and converting it to large amounts of pressure. We also figured out that large mass coupled with large acceleration can transmit energy through the squishy bits to the less elastic bones.

Then we figured out that most of the good stuff was located deep inside the body, behind the bones, and began to realize that small forces directed at these places were more effective than large ones targeting well-reinforced areas. (And thus, fencing was born!)

When we use bullets, we are applying all of these principles. The small cross-section allows the bullet to get past bones and deep into the squishy bits. The taper in the front magnifies the pressure at point of impact, which increases the force (and therefore impulse) ensuring that the surface layers fail before the time interval can stretch out too long. The enormous velocity of the bullets ensures that there is plenty of impulse and momentum left over to penetrate deeply.

Great. But what happens when a bullet hits a person? First, the bullet penetrates the outer layers of clothes and skin, then it travels through any subcutaneous fat tissue and/or muscle. Then, and only then, will it start hitting vital areas.

The bad-guy’s body will first register the impact. Bullets often cauterize at the point of impact, so the pain may take a second to register. As the bullet penetrates, capillaries and blood vessels will be torn and bleeding will start immediately. After the bullet penetrates an inch or so, the body will recognize the deep wound and (usually) send the necessary signals to proceed to a state of shock, concurrent with the resultant loss of blood volume (both psychological and hypovolemic shock can result).

If the bullet continues travelling, it may eventually strike an internal organ or major blood vessel. The rules of physics still apply here. The amount of force, impulse, and pressure are still a function of mass, acceleration, and bullet area, and the ability to damage vital organs will be a function of this. By now, the bullet has slowed considerably, but still carries a lot of potential. At this point, some bullets will have fragmented, hopefully wounding multiple areas at once. Other bullets will have deformed to increase the size of the wound channel and rapidly shed energy, and thereby decrease the time interval in which the energy is expended (subsequently increasing the impulse).

Virtually any perforated organ can cause death by exsanguination very quickly. Human organs are big bags of blood, for the most part, and the heart won’t stop pumping to them just because they are now leaking. How long this takes is completely unique to the individual. Some people drop from pain and shock just by being grazed, Roy Benevidez remained upright, and (terrifyingly) functional despite 37 bullet, stab, and shrapnel wounds. Without medical attention, he would have died from these wounds, but the real moral here is: don’t mess with Roy Benevidez, because apparently blood loss and shock don’t really bother him.

Don't f#*% with Roy...

The holy grail of combat shooting is the head/spine shot. Damage to the brain or spine causes instant paralysis and often death. That’s why the skull is so thick. Evolution is clever like that. Perforating the pericardium (the sack that encases the heart muscle) will drop a bad guy almost as quickly, but it is fairly well protected by the sternum and ribs.

Your mileage (and bad guy) may vary.

Finally, the bullet will either lodge in the bad guy, or exit. Exit wounds increase the rate of exsanguination in a subject, decreasing the time before blood loss and the resultant loss of blood pressure cause unconsciousness. Generally, this is a good thing.

Big Hole Theory

Many defensive shooters, and many professional tactical bad-ass types adhere to the “big-hole” theory. This is as simple as it sounds. Big bullets travelling at very high velocities kill bad guys faster and better. Obviously, the physics of this theory is compelling. I don’t have to re-hash previous sections for everyone to realize that delivering a lot of energy engenders a higher potential for damage than then smaller quantities of same.

Case closed then! Everybody run out and get a 500 Smith and Wesson and we’ll call it a day! Wait? Where are you all going? Whattaya mean you want more than 5 rounds at a time and a weapon that weighs less than a ‘67 De Soto? Yeah I know. There is more to it than just strapping the largest cannon you can to your body and going. The obvious issues with the Big Hole theory are size, and ammo capacity. Big bullets take up a lot of space. So you get fewer of them. Virtually all require a large-framed weapon, often a revolver, that is difficult and uncomfortable to carry daily. Every time I see a movie where someone casually whips a Desert Eagle 50AE out from their waistband and starts blithely blasting away I want to bang my head on the coffee table. I have carried some big guns, and it is a chore.

Furthermore, these powerful rounds are very loud. Discharging a .44 magnum indoors can result in permanent hearing damage. Nobody ever told that to Dirty Harry, obviously. The poor guy is going to be deaf before he turns fifty. These weapons are also difficult to shoot, and require a lot of painful practice, and expensive ammo.

That being said, you can’t deny the sheer simplicity of the Big Hole theory.

The “capacity and shot placement” crowd

Another major school of thought is that smaller, less energetic rounds, when applied properly, are just as lethal as bigger bullets. This is by far the most popular method currently employed by defensive shooters. Basically, the plan is to carry more bullets, and shoot the bad guy properly. In this vein, the vast majority of defensive shooters carry some sort of weapon chambered in 9mm Luger.

The average 9mm round leaves the muzzle at about 1000 feet per second and with about 300 ft-lbs of force. FBI tests (http://www.firearmstactical.com/ammo_data/9mm.htm ) demonstrate that this will penetrate between 10 and 15 inches of ballistics gelatin (do I need to explain what that is? Google it, people!). 9mm obviously carries enough juice to get to those precious organs, as we can plainly see. Furthermore, there are 20-round magazines for medium-framed automatics out there that are reliable, accurate, and very concealable.

Allright…lets all go get a 9mm pistol! Wait…Oh no. More caveats?

When examining the physics ballistics gel results, it is important to note that while penetration is a good way to get to the organs, we can also use it to judge the rate at which the energy is dumped into the target. While 11 inches of penetration (of gel) indicates that the bullet will go deep enough to hit organs, it also tells us a little bit about the comparative impulse.

If a 9mm bullet carries 300 ft-lbs of force and deposits it all in 11” of gel, and a .357 delivers 700 ft-lbs of force and deposits all of it in 11” as well, which had the greater impulse? (Assume penetration as a linear function of interval, you geeks out there)

Answer: .357. Same penetration, greater force, means larger impulse, or more rapid deposit of energy. This equates to more damage along the wound axis and less deflection. The obvious weakness of the small bullet is less energy, and less impulse. This means it will not cause as much damage over the wound channel as more energetic bullets, and it is more likely to deflect off bones, or around denser tissues.

Magic Bullets

Since the dawn of bullets, the whole “big bullet vs. little bullet” debate has raged on and on; and both sides are right. To compromise, lots of improvements have been made to increase the lethality of smaller bullets, and the reaction has of course been that whatever makes a little bullet better also makes a big bullet better. The most common attributes attributed to bullet lethality are muzzle energy (usually measured in ft-lbs), penetration (measured in inches of ballistic gelatin), and energy expenditure (impulse, as determined by energy and penetration). Thus many innovations have been employed to maximize one or more of these factors. I’ll try to briefly break down the three most common options here:

FMJ-

“Full Metal Jacket.” The first major innovation in the modern bullet was to wrap the hunk o’ lead at the front with a copper jacket. Copper is harder than lead, and so the bullet was now a little stiffer upon initial impact. The goal being to have the bullet hold its shape until the outer layers of clothes and fat were penetrated. By holding its shape, the bullet keeps its pointy nose, and thus maintains high pressure on impact. The bullet will eventually deform, but generally, it will do so after initial penetration. This causes the bullet to penetrate more deeply, and not expend energy on the surface where it does little good. This is great for bullets with high-velocity, and low mass. Think 9mm.

The hollow point-

Basically, you take the nose of your standard bullet, and hollow it out. This causes the bullet to expand in a very uniform, mushroom pattern. The result is a bullet that creates a much larger wound channel than it would otherwise, and rapid energy expenditure (higher impulse). This can come at the cost of some penetration, so it is most effective when used in high-mass, low speed rounds, like the .45ACP.

JHP-

This stands for “Jacketed Hollow Point.” All the best aspects of the previous two categories combined. You get the extra penetration provided by the copper jacket, with the wide wound channel and higher impulse of the hollow point. It's damn near perfect. Your bullet gets good and deep without shedding too much energy, only to expand and dump it all right where you want it. These are the most common type of self-defense round in the world; it is perfect in nearly every caliber with the exception of the very small, low energy rounds found in mouse guns. In a powerful revolver, these are positively devastating.

There are numerous other options, but these are the most common. For an exercise in confusion, look up some of these:

Many shooters will also regale you with stories of “hydrostatic shock” when discussing self-defense ammunition. This refers to the damage done to a human body as a direct result of pressure waves created by ballistic trauma. Basically, when a bullet hits you, it creates an area of extremely high fluid pressure at the point of impact which is then transferred via the body’s natural fluid pathways to areas not struck by the bullet. The fact that this occurs is not debatable. It has been measured and documented under laboratory conditions. The effects of it as it pertains to self-defense ammunition however, is meat for many a contentious argument.

A WWII trauma surgeon named Frank Chamberlain noticed the effect:

...liquids are put in motion by ‘shock waves’ or hydraulic effects... with liquid filled tissues, the effects and destruction of tissues extend in all directions far beyond the wound axis

It should be noted that most of the wounds he saw were caused by the common battle rifles of the time, which delivered anywhere from five to ten times the energy than common handgun rounds. However, his research was picked up again by a Vietnam-era trauma surgeon named Fackler; who posited that a common medical instrument, the lithotriptor, produced greater hydraulic pressure waves than a bullet could with no ill effects to the recipient. This compelling point put a large hole in the hydrostatic shock theory. Fackler also noted that there were very few documented incidents of internal trauma anywhere beyond the bullet axis in his patients. Of course, by Vietnam, the common battle rifles were significantly less powerful than their WWII predecessors. Fackler did note the existence of minor contusions and stresses in internal organs and structures along the wound axis, but not in the wound channel [COLOR="rgb(255, 140, 0)"](From: Fackler ML, Gunshot Wound Review, Annals of Emergency Medicine; 1996.)[/COLOR], but most agree that these would not contribute greatly to stopping an enemy.

I will spare you a large and boring dissertation on blast pressure waves and the human body; mostly because I do not have the academic chops to do much more than parrot more learned individuals than me. The research regarding the damage caused by hydrostatic shock is extensive and ongoing, and the results are a categorical “nobody really knows.” My interpretation of the research seems to be that while an observable phenomenon, hydrostatic shock is insignificant in handgun calibers, and therefore should not be considered when selecting handgun ammunition. This is the stance of the FBI as well, based upon their testing. ( http://www.firearmstactical.com/hwfe.htm )

You may also hear about “neural shock” and various other sundry and esoteric factors, but the reality is that no single military or law-enforcement organization endorses any of these more bizarre factors, due to the low quantity and over all poor quality of the research backing them. They are often paired with some company’s proprietary uber-bullet that costs too much and performs no better than any other bullet.

So what do I pick?

Here’s the ugly truth as I see it:

• A $.13 9mm FMJ to the head kills the bad guy just as dead as $2.00 500S&W. This is not debatable.

• If you look at the physics empirically, you can certainly say with a high degree of probability that more energetic bullets produce larger, grislier, and more traumatic wounds than less energetic bullets.

• Modern JHP bullets have greatly increased the lethality of all calibers.

• Every bullet is deadly

Not a whole lot of help there, is it? It gets worse. There is no such thing as a guaranteed one-shot stop. Too many variables factor into the biomechanics of a gunshot wound to promise anything. Ask Roy Benevidez about it.

That being said, shot placement greatly increases the lethality of any bullet. As does multiple hits. Being able to reliably double-tap your bad guy center mass with 9mm or .38 special will go a lot further (from a self-defense standpoint) than winging him with a hand cannon. At the same time, being able to double tap with .40 S&W or .357 magnum increases your chance of a stoppage even more. I am not speaking any revolutionary truths here. We are still just doing math. If you can hit the bad guy reliably with a small bullet, than you are doing well and have a reasonable chance of stopping him, and if you can do it with the big stuff your chances get even better.

The vast overwhelming body of research and statistical analysis seems to concur that 9mm Luger is sufficient to cause stoppage in the majority of bad guys. Which does not mean that .380, .32, and other less energetic rounds won’t stop bad guys, it just means that most military and law enforcement organizations feel that these calibers don’t do it fast enough often enough for practical use by professional shooters. Since most bad guys abandon their assault and run away at the mere sight of a firearm, it is unfair to rule out the smaller calibers. Similarly, the condition of suffering a gunshot wound of any caliber is typically sufficient to cause psychological shock to your assailant; and subsequently end the threat to yourself.

All you reactionary types don’t get cranky with me for saying that. Reality is reality, and if just brandishing a firearm causes 95% of bad guys to go bother someone else, than 95% of the time caliber is irrelevant. That is not opinion. That is math. Bad guys want victims, not opponents; and presenting yourself as an opponent rather than a victim is the cornerstone of most self-defense strategies armed or otherwise. So lay off the mouse guns. If that is all you can handle, it is certainly much better than no gun at all (you really should try to go with 9mm at least, though…).

The Answer:

Despite my attempts to blind you with science, dear reader, I must confess that this result is still just the opinion of the author. I like the opinion, though, and find it highly defensible. So read on and do what you will with it. Without further ado, these are my commandments for self-defense weapon, holster, and ammo selection:

1: Thou shalt carry as much gun as you can safely and competently handle.

This means you carry a weapon you can comfortable hold with the highest energy round you can reliably and safely make center mass hits with at combat ranges. Period. If you can handle a big, powerful round safely and competently, you should be using it. If you can only handle lower-energy rounds, don’t feel bad…they get the job done, too. Ignore idiots who say otherwise. Competency is more important than raw power or ammo capacity. You can’t miss fast enough to win a gunfight, or power your way through bad shooting. Determining your choices will depend on your size, skill, and recoil tolerance, as well as any relevant laws for your state.

2: Thou shalt practice often.

This means that you select a weapon and round that you can afford to practice with often. Once a year is not enough, people. I like to get to the range twice a month in the good weather, and typically get through 300-500 rounds. This can get pricey with some calibers, but .357 magnum can chamber the much cheaper .38 special, and low-cost reloads are readily available for most defensive calibers. Bargain hunting is key. Buy in bulk whenever possible. If you can’t afford to practice with it, you can’t afford to carry it. Guns are not jewelry, take them seriously or don’t carry one.

3: Thou shalt avoid “Tactical Ted”

When you seek out firearms instruction or advice, avoid wannabe operators in tactical vests carrying weapons that look like props from a sci-fi movie. You are not a professional shooter, you don’t need professional equipment. You need simple, reliable equipment suited to your lifestyle. You need practical advice about the real world, not the paranoid fantasies of a Walter Mitty. I have found that virtually every region has a local NRA instructor or training facility that caters to the everyday defensive shooter. Go there. Now. Why are you still reading this?

4: Thou shalt buy a decent holster.

Also known as the “Plaxico Burress” clause, this means that you will carry your weapon properly. This prevents the embarrassing and potentially legally actionable “Oops, I dropped my Glock” moment; as well as the “Ow, I blew my foot off” moment.

5: Know thy tool.

Get your mind out of the gutter. This means that you understand how your weapon operates, mechanically. You should be able to disassemble, clean, and clear malfunctions without assistance. This prevents you from finding yourself helpless when the inevitable mechanical failure occurs, and prevents you from looking like an ignorant dumbass in general. Guns are dangerous; know how yours works for everyone’s sake.

There you have it. The results of this little jaunt are fairly intuitive. There is no ideal handgun round for everyone. There are too many factors to consider for this to be the case. But your selection can be optimized based on these factors: Comfort, Competency, and Power. Any weapon and ammunition combination that maximizes these factors for you is your ideal round. Find it, and get to practicing.

Last edited by Scrapper; 5/13/2010 6:39am at .

And lo, Kano looked down upon the field and saw the multitudes. Amongst them were the disciples of Uesheba who were greatly vexed at his sayings. And Kano spake: "Do not be concerned with the mote in thy neighbor's eye, when verily thou hast a massive stick in thine ass".

And lo, Kano looked down upon the field and saw the multitudes. Amongst them were the disciples of Uesheba who were greatly vexed at his sayings. And Kano spake: "Do not be concerned with the mote in thy neighbor's eye, when verily thou hast a massive stick in thine ass".

I am a bit skeptical about the cauterization of bullet wounds, having never seen it. I have yet to use a firearm on a human being, but having used various types of bullets on many, many animals, I can say that shot placement is the most important factor. With that being said; mass, diameter, bullet construction and velocity are also very important. There must be a proper mix of all of those ingredients for a bullet to be effective and even then they don't always work as intended.

As a former Navy man, I have an affinity for the 45 ACP FMJ. I'm in love with my USP compact 45, because it's huge but just small enough to get a decent conceal in the small of my back. And, it makes really big holes.

The important point is that I hit the range every 4-6 weeks and put 50-100 rounds through it (depending on how cheap and if the local dealers even have 45s that week). I agree that the caliber of the gun is irrelevant if you are unable to put 2-4 rounds on target on demand. But, caliber also doesn't matter if you are mentally not up to the task of being able to put two in the chest and one into the cranio-ocular cavity, should you find yourself unlucky enough to be in a situation that you would have to draw your gun.

gotta watch the physics formulas though... the summation of the forces is mass x acceleration and newton's cradle is an example very nearly perfectly elastic collision.

vector calculus is great...

F=MA is always a slippery slope. It was either write a 10-page paper on Newtonian physics or go with the simple vernacular for effect. ANd you are right...i juxtaposed my elastic and inelastic collision, dammit. Fixing now you bastard.

And lo, Kano looked down upon the field and saw the multitudes. Amongst them were the disciples of Uesheba who were greatly vexed at his sayings. And Kano spake: "Do not be concerned with the mote in thy neighbor's eye, when verily thou hast a massive stick in thine ass".

I really expected people to be shouting at all the things I got wrong by now...

Where are the Dirty Harry's and Tactical Ted's?

And lo, Kano looked down upon the field and saw the multitudes. Amongst them were the disciples of Uesheba who were greatly vexed at his sayings. And Kano spake: "Do not be concerned with the mote in thy neighbor's eye, when verily thou hast a massive stick in thine ass".

I really expected people to be shouting at all the things I got wrong by now...

Where are the Dirty Harry's and Tactical Ted's?

And lo, Kano looked down upon the field and saw the multitudes. Amongst them were the disciples of Uesheba who were greatly vexed at his sayings. And Kano spake: "Do not be concerned with the mote in thy neighbor's eye, when verily thou hast a massive stick in thine ass".